KR20070006744A - Electrophoretic display panel - Google Patents

Abstract

An electrophoretic display panel (1), comprises a plurality of picture elements (2); and drive means (100), for providing reset pulses prior to application of grey scale pulses and for providing shaking potential differences in between application of reset and grey scale potential differences. The display panel comprises two or more interspersed groups of display elements. Each group is supplied with its own application scheme (1, II) of shaking potential differences, the application schemes for shaking potential differences differ from group to group in such manner that the occurrence of shaking potential difference differs between said groups for at least some transitions. ® KIPO & WIPO 2007

Description

Electrophoretic Display Panel {ELECTROPHORETIC DISPLAY PANEL}

The present invention,

An electrophoretic medium comprising charged particles;

A plurality of pixels;

An electrode associated with each pixel for receiving a potential difference, wherein the charged particles can occupy an extreme position near the electrode and an intermediate position between the electrodes; The extreme position being associated with an extreme optical state; And

As driving means, for each of a plurality of pixels

A reset potential difference having a reset duration and a reset value during a reset period for causing the charged particles to substantially occupy one of the extreme positions, and subsequently

A gray scale potential difference for the particles to occupy a position corresponding to the image information and

A series of shaking potential differences during the shaking period between the reset potential difference and the application of the gray scale potential difference.

An electrophoretic display panel comprising drive means, arranged to provide a.

The invention also relates to a method for driving an electrophoretic display device comprising a plurality of pixels, in which a reset potential difference is applied to a pixel of the display device and reset before applying a gray scale potential difference to the pixel. A series of shaking potential differences is applied between the potential difference and the application of the gray scale potential difference.

One embodiment of an electrophoretic display panel of the type mentioned in the opening paragraph is described in international patent application WO 03/079323.

In the above-mentioned electrophoretic display panel, each pixel has an appearance determined by the position of the particles during display of the image. However, the position of the particles depends not only on the potential difference but also on the history of the potential difference. Due to the application of the reset potential difference, the dependence on the hysteresis of the appearance of the pixel is reduced because the particles substantially occupy one of the extreme positions prior to the application of the gray scale potential difference. Thus, the pixel is reset to one of the extreme states each time. Within the structure of the present invention "reset" refers to the application of a potential difference which is not long enough to bring the pixel to an extreme state, but not longer than necessary, i.e. a reset pulse is sufficient to bring the pixel to an extreme state. But in practice it is no longer than necessary to bring the pixel to the extreme. Subsequently, as a result of the image potential difference, the particles occupy a position for displaying a gray scale corresponding to the image information. "Gray scale" will be understood to mean any intermediate state. When the display is a black and white display, the "gray scale" is actually associated with the hue of gray, and when other types of color elements are used, the "gray scale" includes any intermediate state between extreme states. Will be understood.

The pixel is reset when the image information is changed. A series of shaking potential differences is applied between the reset potential difference and the application of the gray scale potential difference. These potential differences are referred to in WO 03/079323 as "preset potential differences". The shaking potential difference is sufficient to emit electrophoretic particles from a static state in one of the two electrodes, but includes a pulse with an energy that is too low to reach the other of the electrodes. The basic mechanism is that after the display device is switched to a predetermined state (e.g. a black state), the electrophoretic particles become static, so when the subsequent switching is white, the momentum of the particles is close to zero since their starting speed is close to zero. It can be explained that it is low. This results in a long switching time. Application of a shaking (or “preset”) pulse increases the momentum of the electrophoretic particles and thus shortens the switching time.

Despite the beneficial effects of the application of the shaking (or “preset”) potential difference, the inventors have realized that they have a negative effect during the transition from one image to another at the end of the reset period. When the gray scale image is reset, a full black and white image is produced. This black and white image is maintained during the application of the shaking potential difference. Thus, a visible rough black and white image can be seen during this period. This transition from one image with gray to another image with gray tones, through a fully black and white image where a rough, gray tone-free image can be seen, disturbs the viewer.

It is an object of the present invention to provide a display panel of the type mentioned in the opening paragraph which can provide a more favorable transition from one image to another.

The object is that the plurality of pixels comprises a group of two or more dispersed pixels, the driving means being arranged to provide each pixel group with its own application structure of the shaking potential difference, wherein the application of the shaking potential difference is such that The shaking time period applied to the groups differs for each group in a manner that is perfectly consistent for at least some transitions of pixels from the initial optical state through the extreme optical state to the final optical state during the time difference, wherein the time difference for each group By at least 25% of the longest shaking time period. The time difference is in particular the onset time of the shaking potential difference, the end time of the shaking potential difference, especially when the shaking time periods for the groups are of the same length, or when the shaking potential differences with different durations are onset, end time, or both. That is, it may be due to the difference between the start or end of the shaking time period.

Resetting a pixel to one of the extreme states requires the application of a reset potential difference for the other pixel. When all devices are reset to black, a white image is produced. The shaking pulse is then applied during the shaking time period and then the gray scale potential difference is applied.

The concept of the present invention is to divide the display panel and thereby divide the image displayed on the display panel into two or more pixel groups. This disturbing effect occurs for each group of pixels. However, the entire image consists of two or more internally blended images and the sum of the effects of the groups alleviates or at least reduces the effects. To do this, the period during which the complete black and white image is visible, i.e., the period during which the shaking pulses are applied, is different for each group, i.e. the time between the shaking time periods is not completely identical and the difference, i.e. the period when the shaking periods are not black and white images, is different. Occupies a significant portion (at least 25% in the preferred embodiment, at least 50% in the preferred embodiment, at least 75% in the preferred embodiment, preferably 100%), during which time black and white images are visible. In other words, groups are distributed, i.e., images produced by different groups are merged into one image when the viewer views at a normal viewing distance (ie without using a magnifying glass or other such device). Each group, when viewed on its own, creates a disturbing effect that produces a rough, monochrome image between the gray tones containing the image. However, since the duration of this effect is different for at least some of the transitions in each group and the groups are dispersed, forming a single image in the human eye, the human eye is leveled with complex and less disturbing effects. And smoother image transitions occur. "Distributed" means that images from individual groups are merged into one image when viewed by the viewer from normal or standard viewing distances (approximately three times greater than the diagonal length of the screen). Some examples of such distributed groups are, for example, groups in which even rows or even columns belong to one group and odd rows or columns belong to another group. The size of the columns and rows of the display devices are not individually discernible by the viewer at the normal viewing distance, and therefore division into groups containing adjacent rows will fuse the two images into one image. If the size of the rows and columns is small enough, the groups may also include pairs or alternating bundles of rows or columns that include fewer (1, 2, 3, or 4) rows or columns. A small checkerboard shape can also be used. Non-distributed groups are, for example, a group in which one group includes the left half and the right half of the display screen, or one group includes the upper half and the lower half of the display screen. These groups cover different parts of the display screen and the viewer will simply see the same effect twice, with slightly different top (right) half and then bottom (left) half. The time difference is at least 25% of the time that the black and white image is visible, in order to enable an effective smoothing effect, preferably 50% or more.

Preferably the drive means are arranged such that the application structure for the application of the shaking potential difference is alternated between groups of pixels between frames.

Application of different shaking signals between groups has the above-mentioned positive effect of reducing the harness of image conversion. However, even if the application of shaking pulses in different structures for different groups has a positive effect, looking further in time, it is best for all groups of pixels to have substantially the same history of application of shaking potential differences. By alternating the structure for application of the shaking potential difference between groups of pixels between images, the difference between groups of pixels is minimized. For example, if two groups of pixels A and B are used and two application structures I and II are used for applying the shaking potential difference, in the first frame, structure I is used for group A and structure II is group B In the next frame, structure II is used for group A, structure II is used for group B, and in the next frame, structure I is used for group A and structure II is used for group B. And so on. With two or more groups, circulation and rotation of the structure will be used, which corresponds to "alternating" under the inventive concept. In the preferred embodiment the structures are alternating with each change of frame, but under the broader concept of the invention, the structures can be alternating for each n frames, where n is a small number such as 1, 2, 3.

In one embodiment the drive means are arranged to supply each group with its own structure of shaking potential difference and the application structure for the shaking potential difference differs only by a time difference in each group irrespective of the transition.

In this embodiment, the time difference (delay) is established between the application of the shaking potential difference. The authorization structure is basically the same for each group, but shifts in time by a delay. The application of pulses starts and ends at different times for different groups. This is a simple embodiment and does not require more than the same simple waveform delay for each waveform.

Other additional embodiments for different transitions with different durations of shaking potential difference in different groups are given in the examples.

)동안, 초기 광학 상태로부터 극단의 광학 상태를 통해 최종 광학 상태로 화소의 적어도 일부 전이에 대해 완전히 일치하는 방법으로 각 그룹마다 다르며, 상기 시간차는 각 그룹에 대해 가장 긴 쉐이킹 시간 기간의 적어도 25%인 것을 특징으로 한다.In the method according to the invention, in the method according to the present invention, before the reset potential difference is applied to the pixel, the pixel is applied to the pixel of the display device, and the shaking potential difference is applied during the shaking time period between the application of the reset potential difference and the gray scale potential difference. And wherein the plurality of pixels comprises at least two distributed pixel groups, each pixel group being provided with its own application structure of shaking potential difference, and the application structure to the shaking potential difference is a shaking time period during which a shaking potential difference is applied to the group. Is the time difference (

), The time difference is different for each group in a way that is perfectly consistent for at least some transitions of pixels from the initial optical state to the extreme optical state to the final optical state, wherein the time difference is at least 25% of the longest shaking time period for each group. It is characterized by that.

These and other aspects of the display panel of the present invention will be further described with reference to the drawings.

1 is a schematic front view of a display panel.

2 is a schematic cross sectional view along II-II of FIG. 1;

3 is a schematic cross-sectional view of a portion of a further example of an electrophoretic display device.

4 is a schematic equivalent circuit diagram of the image display device of FIG.

Figure 5a schematically illustrates the potential difference as a function of time for a pixel for one transition.

5b schematically illustrates the potential difference as a function of time for the pixel for further transitions.

Figure 6a schematically illustrates the potential difference as a function of time for pixels for additional transitions.

6b schematically illustrates the potential difference as a function of time for another pixel for additional transitions.

FIG. 7 shows an image showing an average of first and second appearances due to a reset potential difference. FIG.

FIG. 8 shows an image showing an average of first and second appearances due to a reset potential difference. FIG.

9 schematically illustrates a potential difference as a function of time for a pixel;

10 shows the transition from the initial gray tone image A to the next gray tone image B, via the intermediate monochrome image I. FIG.

11 shows a first drive structure;

)이 추가된다는 점에서 도 11의 구동 구조와 다른 제 2 구동 구조를 도시한 도면.12 is the delay time (

Is a second drive structure different from the drive structure of FIG. 11 in that it is added.

FIG. 13 illustrates the effect of two distributed groups using the structure of FIGS. 11 and 12.

14 illustrates a further embodiment of the present invention.

15 shows another relationship between shaking period times.

Corresponding portions in all figures are usually referred to by the same reference numerals.

1 and 2 show an embodiment of a display panel 1 having a first substrate 8, a second opposing substrate 9 and a plurality of pixels 2. Preferably, the pixels 2 are arranged along a substantially straight line in a two-dimensional structure. Other arrangements of the pixels 2, for example honeycomb arrangements, are alternatively possible. An electrophoretic medium 5, with charged particles 6, is present between the substrates 8, 9. The first and second electrodes 3, 4 are associated with each pixel 2. The electrodes 3 and 4 can receive the potential difference. In FIG. 2, the first substrate 8 has a first electrode 3 for each pixel 2, and the second substrate 9 has a second electrode 4 for each pixel 2. . The charged particles 6 may occupy an extreme position near the electrodes 3, 4 and an intermediate position between the electrodes 3, 4. Each pixel 2 has an appearance determined by the position of charged particles between the electrodes 3, 4 for displaying an image. The electrophoretic medium 5 is for example known from US 5,961,804, US 6,120,839 and US 6,130,774 and can be obtained, for example, from E ink company. As an example, the electrophoretic medium 5 comprises black particles 6 negatively charged with white fluid. When the charged particles 6 are near the first extreme position, that is, near the first electrode 3, the potential difference is, for example, 15V, so that the appearance of the pixel 2 is, for example, white. It is thought that the pixel 2 is observed from the side of the second substrate 9. When the charged particles 6 are near the second extreme position, that is, near the second electrode 4, the appearance of the pixel 2 is black because the potential difference is the opposite polarity, that is, -15V. When the charged particles 6 are in one of the intermediate positions, i.e. between the electrodes 3, 4, the pixel 2 has one of the intermediate appearances, for example light grey, medium grey, dark grey. , These are the gray levels between white and black. The drive means 100 is such that the particles 6 have a reset potential difference with a reset value and a reset duration such that the particles 6 can substantially occupy one of the extreme positions and subsequently the particles 6 are image information. It is arranged to control the potential difference of each pixel 2 so as to become an image potential difference so as to occupy a position corresponding to.

FIG. 3 shows an electrical system, for example of the size of some display elements, including a base substrate 32, which is an electrophoretic film with an electronic ink present between two transparent substrates 33, 34 such as polyethylene, for example. A cross-sectional view of a portion of a further example of a phoretic display device 31 is schematically shown, one of which is provided with a transparent image electrode 35 and the other with a transparent counter electrode 36. . The electronic ink includes a plurality of microcapsules 37 of approximately 10 to 50 microns. Each microcapsule 37 includes positively charged white particles 38 and negatively charged black particles 39 floating in fluid F. When a positive electric field is applied to the pixel electrode 35, the white particles 38 move towards the microcapsules 37 facing the counter electrode 36 and the display element is visible to the viewer. At the same time, the black particles 39 move to the opposite side of the microcapsules 37 hidden from the viewer. By applying a negative electric field to the pixel electrode 35, the black particles 39 move towards the microcapsules 37 opposite the counter electrode 36 and the display element appears dark to the viewer (not shown). When the electric field is removed, particles 38 and 39 remain achieved and the display is bistable and consumes virtually no power. The particles can be black and white but can also be color. In this respect "gray scale" will be understood to mean any intermediate state. When the display is a black and white display, "gray scale" is actually associated with the hue of gray, and when other types of color elements are used, it is understood that 'gray scale' includes any intermediate state between extreme states. Will be.

4 schematically shows an equivalent circuit of an image display device 31 comprising an electrophoretic film laminated on a base substrate 32 provided with an active switching element, a row driver 46 and a column driver 40. Preferably, counter electrode 36 is provided on a film comprising encapsulated electrophoretic ink, but may alternatively be provided on a base substrate in the case of an operation using a coplanar electric field. The display device 31 is driven by an active switching element, which in this example is a thin film transistor (TFT) 49. It comprises a matrix of display elements at the intersection of the row or selection electrode 47 and the column or data electrode 41. The row driver 46 continuously selects the row electrode 47, while the column driver 40 provides a data signal to the column electrode 41. Preferably, processor 45 first processes incoming data 43 into a data signal. Mutual synchronization between the column driver 40 and the row driver 46 occurs via the drive line 42. The select signal from the row driver 46 selects the pixel electrode 42 through the thin film transistor 49, the gate electrode 50 of the transistor is electrically connected to the row electrode 47 and the source electrode 51 is It is electrically connected to the column electrode 41. The data signal present in the column electrode 41 is transmitted via the TFT to the pixel electrode 52 of the display element connected to the drain electrode. In the embodiment, the display device of FIG. 3 also includes an additional capacitor 53 at the location of each display element 48. In this embodiment, an additional capacitor 53 is connected to one or more storage capacitor lines 54. Instead of the TFT, other switching elements such as diodes, MIMs, etc. may be applied.

As an example, the appearance of the pixels of the subset is light gray, indicated by G2, before application of the reset potential difference. In addition, the image appearance corresponding to the image information of the same pixel is dark gray, indicated by G1. As an example, the potential difference of the pixels is shown as a function of time in a of FIG. The reset potential difference, for example, has a value of 15 V and appears from t ₁ to t ₂ , where t ₃ is the maximum reset duration, ie the reset period (Preset). Reset duration and maximum reset duration are, for example, 50 ms and 300 ms, respectively. This causes the pixel to have a substantially white appearance, denoted W. The picture potential difference (gray scale potential difference) appears from t ₄ to t ₅ (P _{grey-scale driving} ), and has a value of, for example, -15V and a duration of, for example, 150 ms. This causes the pixels to have an appearance that is dark gray (G1) for displaying an image. A series of shaking potential differences between the reset potential difference and the application of the gray scale potential difference is applied between t ₃ and t ₄ , denoted P _shaking in the figure.

As a further example, the potential difference of the pixels is shown as a function of time in b of FIG. The appearance of the pixel is dark gray (G1) before the application of the reset potential difference. In addition, the image appearance corresponding to the image information of the pixel is light gray (G2). The reset potential difference, for example, has a value of 15 V and appears from time t ₁ to time t ₂ . The reset duration is for example 150 ms. As a result, the pixel has an appearance of being substantially white (W). The gray scale or picture potential difference appears from time t ₄ to time t ₅ (P _{grey-scale driving} ) and has a value of, for example, -15V and a duration of 50ms, for example. This causes the pixels to have a light gray (G2) appearance to display an image. A series of shaking potential differences is applied during the _shaking period P _shaking .

In another variant of the embodiment, the drive means 100 is further arranged to control the reset potential difference of each pixel so that the particle 6 can occupy the extreme position closest to the position of the particle 6 corresponding to the image information. As an example, the appearance of the pixel is light gray (G2) prior to application of the reset potential difference. In addition, the image appearance corresponding to the image information of the pixel is dark gray (G1). In this example, the potential difference of the pixels is shown as a function of time in a of FIG. The reset potential difference has a value of, for example, -15V and appears from time t ₁ to time t ₂ . The reset duration is for example 150 ms. Due to this, the particles 6 occupy a second extreme position and the pixel is substantially black, denoted B, which is closest to the position of the particle 6 corresponding to the image information, ie the pixel 2. Has a dark gray appearance G1. The gray scale or image potential difference appears from time t ₄ to time t ₅ and has a value of for example 15V and a duration of 50ms for example. Again, a series of shaking pulses is applied during P _shaking . As a result, the pixel 2 has an appearance of dark gray G1 for displaying an image. As another example, the appearance of the other pixels is light gray (G2) prior to application of the reset potential difference. In addition, the image appearance corresponding to the image information of this pixel is substantially white (W). In this example, the potential difference of the pixels is shown as a function of time in b of FIG. The reset potential difference, for example, has a value of 15 V and appears from time t ₁ to time t ₂ . The reset duration is for example 50 ms. Due to this, the particles 6 occupy a first extreme position and the pixel has a substantially white appearance W, which is closest to the position of the particle 6 corresponding to the image information, ie the pixel 2 is It has a substantially white appearance. The picture potential difference appears from time t ₄ to time t ₅ and has a value of 0V since the appearance is already substantially white for display of the picture. In this case, it is not necessary to use shaking pulses and the particles do not necessarily have to be shaken. {Ie, optional and can be shaken if desired}. For transitions where the final gray scale is extreme (black or white), the gray scale potential difference need not be applied after reset since the pixel is in the intended optical state after reset. For this transition, it is not necessary to use shaking pulses and are generally not useful. For transitions where the original optical state (ie, before the possible application of a reset pulse) is the final state, there is no need to use a reset pulse, and consequently no shaking pulse. Within the framework of the present invention, transitions are compared in each group using shaking pulses, and the periods P _shaking for the groups are compared with each other and the difference is determined.

In FIG. 7 the pixels are arranged substantially along a straight line 70. The pixel has a first appearance (eg white) which is substantially the same when the particles 6 occupy one of the substantially extreme positions (eg the first extreme position). The pixel has a substantially identical second appearance (eg black) when the particles 6 substantially occupy the other of the extreme positions (eg the second extreme position). The drive means are further arranged to control the reset potential difference of the subsequent pixel 2 along each line 70 so that the particles 6 can occupy extreme positions which are substantially not identical. 7 shows an image showing the average of the first and second appearances as a result of the reset potential difference. The picture appears substantially neutral gray.

In FIG. 8 the pixels 2 are arranged along a substantially straight row 71 and along a substantially straight column 72 which is substantially perpendicular to this row in a two-dimensional structure, each row 71 being pre-determined. It has a first number of pixels (eg, 4 in FIG. 8), and each column 72 has a second predetermined number of pixels (eg, 3 in FIG. 8). The pixel has a substantially identical first appearance, for example white, when the particles 6 occupy one of the extreme positions, for example the first extreme position. The pixel has a substantially identical second appearance (eg black) when the particles 6 occupy substantially one of the other extreme positions (eg the second extreme position). The drive means are further arranged to control the reset potential difference of the subsequent pixel 2 along each row 71 so that the particles 6 can occupy an extreme position that is not substantially the same, and the drive means is provided with particles 6. ) Are further arranged to control the reset potential difference of the subsequent pixel 2 along each column 72 so that they may occupy extreme positions that are not substantially identical. 8 shows an image showing the average of the first and second appearances due to the reset potential difference. The picture is substantially neutral gray, which is somewhat smoother than in the previous embodiment.

In a variant of the device, the driving means is further arranged to control the potential difference of each pixel to be a preset potential difference sequence before the reset potential difference. Preferably, the sequence of preset potential differences has a preset value and an associated preset duration, the preset values in the sequence are alternating signs, and each preset potential difference is not sufficient to emit particles 6 appearing at one of the extreme positions from the original position. This is sufficient, but indicates insufficient preset energy to allow the particles 6 to reach other of the extreme positions. As an example the appearance of the pixel is light gray prior to the application of the sequence of preset potential differences. In addition, the image appearance corresponding to the image information of the pixel is dark gray. As an example of this, the potential difference of the pixels is shown as a function of time in FIG. In this example, the sequence of preset potential differences has four preset values, subsequently 15V, -15V, 15V and -15V, applied from time t ₀ to time t ₁ . Each preset value is applied for 20 ms, for example. Subsequently, the reset potential difference has a value of, for example, -15 V and appears from time t ₁ to time t ₂ . The reset duration is for example 150 ms. Due to this, the particles 6 occupy a second extreme position and the pixel has a substantially black appearance. The picture potential difference appears from time t ₃ to time t ₄ and has a value of, for example, 15V and a duration of, for example, 50ms. This causes the pixel 2 to have a dark gray appearance to display an image. Without being bound by the specific description for the mechanism based on the positive effect of the application of the preset pulse, the application of the preset pulse has the same effect as the application of the shaking pulse between the reset and the gray scale driving potential difference, i.e., the application of the preset pulse It is estimated that the momentum of the migrating particles is increased, thus shortening the switching time, i.e., the time required to achieve the changeover (change of appearance). The electrophoretic particles may also be "frozen" by counter ions surrounding the particles after the display device has been switched to a predetermined state, such as for example a black state. When the subsequent switching is made white, these counter ions must be released in a timely manner, which requires additional time. The application of a preset pulse increases the release rate of counter ions to thaw the electrophoretic particles and thus shorten the switching time.

As mentioned above, the grayscale accuracy in the electrophoretic display is strongly influenced by image history, residence time, temperature, humidity, side unevenness of the electrophoretic foil, and the like. The accurate gray level using the reset pulse can be achieved since the gray level is always achieved from the reference black (B) or from the reference white state (W) (two extreme states). The pulse sequence usually consists of three to four parts: a first shaking pulse (optionally also later referred to as shake 1), a reset pulse (during P _reset ), a shaking pulse (P _shaking ) and a grayscale drive pulse (P _{gray scale). driving} ).

As explained in the example given above, a series of shaking potential differences are used. The application of the reset potential drives the image to a full black and white image, which is maintained for a period of time, ie during P _shaking . Starting with an image that contains gray tones and switching to another image with gray tones, you see an intermediate image that is completely black and white. This is visible to the viewer. Fig. 10 shows the transition starting from gray tone image A in t = start reset period, while another gray tone image B is generated in t = end gray scale driving period. A medium full black and white image (I) can be seen during P _shaking . Below the figure an arbitrary roughness coefficient H is schematically indicated. Rough images appear during P _shaking . This is a disturbing effect. It is noted, for example, that some lateral shift of the gray tone image, which remains the same in other cases, causes this effect. The rough image is clearly visible. The reason why such a completely black and white image is visible is explained through the example of FIG.

Four transitions (white (W) to dark gray (DG), light gray (LG) to dark gray (DG), dark gray (DG) to black (B), and black (B) to dark gray (DG) Is shown in turn. Each waveform includes a reset signal, a shaking signal (shake 2), and finally a gray scale potential difference (V, t) _drive . At the end of the application of the reset signal, the pixel reaches the final optical state, which is black in this case. This point is indicated by arrow B. From this point on, during shake 2 the pixel remains in its final state, i.e. it is completely black. Similar figures can be made for transitions via extreme white optical states. By time t = 0 the original gray tone image is visible. The pixels turn black and all pixels are black at the end of the reset period. At the beginning of the gray scale driving period, the optical state of the pixel changes again until the end of the gray scale driving period in which the gray tone image B is seen. This structure shows that all the pixels are black during shake 2 (P _shaking ). Full black and white image is seen during this time period. This is shown schematically below the figure.

)만큼 시프트함으로써 지연 시간(

)만큼 지연된다. 도면의 아래 부분에서 볼 수 있는 것처럼 이것은 실제로 문제를 개선시키지 않는다. 완전 흑백 이미지는 지연(

)만큼만 지연된, 동일하게 긴 시간 기간(P_shaking)동안 보인다. 그러나, 이들 구조에 대한 가시 효과가 동일하다고 해도 화소가 사람의 눈이 평균 이미지를 보는 스크린 상에 분포된 2개의 그룹으로 분할된 구조의 결합은 효과를 감소시킨다.FIG. 12 shows the structure of FIG. 11 with one change, wherein the application of the shaking potential difference in this example reduces the overall pulse train to the delay time (

Shift by)

Delay). As can be seen in the lower part of the figure this does not actually improve the problem. Fully black and white images are delayed (

_Seen during the same long time period (P _shaking ), delayed only by. However, even if the visible effects on these structures are the same, the combination of structures in which the pixels are divided into two groups distributed on the screen where the human eye sees the average image reduces the effect.

가 대략 P_shaking과 같거나 클 때(두개의 그룹이 사용된 경우), 매우 점진적인 전환이 달성될 수 있다.Schematically this is shown in FIG. 13. The upper part schematically shows the roughness index (H) for structures I (FIG. 11) and II (FIG. 12), with the disturbing visible effect occurring as described above separately for each group. The overall effect is shown schematically in the lower half of FIG. 13 when the pixels are divided into two dispersed groups, showing a much more gradual change between the images. In this example, the delay time is approximately equal to the shaking period P _shaking . To have an effect, the delay time is at least 25% of the shaking period, preferably at least 50%, more preferably at least 75-100%.

When is approximately equal to or greater than P _shaking (when two groups are used), very gradual conversion can be achieved.

)은 그룹 사이의 인가된 전위차의 파형의 차이를 특성화한다. 기본적으로 두 그룹에 리셋-쉐이킹-그레이 스케일 전위차의 동일한 구조가 각 전이에 대해 인가되며, 오직 펄스 트레인만이 시프트된다. 이 예에서 2개의 그룹이 사용된다. 본 발명의 프레임워크 내에서 2개 이상의 그룹들이 사용될 수 있으며, 일반적 으로 더 많은 그룹이 사용될수록, 전이는 더 매끄럽게 이루어지나, 전자 장치는 더 복잡해진다.11 and 12 show a simple embodiment of the present invention, in which a simple time delay (

) Characterizes the difference in waveform of the applied potential difference between the groups. Basically the same structure of the reset-shaking-gray scale potential difference is applied for each transition in both groups, only the pulse train is shifted. In this example two groups are used. Two or more groups may be used within the framework of the present invention, and in general, the more groups are used, the smoother the transition, but the more complex the electronic device.

)만큼 증가된다는 단점이 있다. 도시된 예에서 시간차는 고정된 시간차이며, 즉, 모든 전이에 대해 동일하며, 이것은 바람직한 실시예이다. 실시예에서 시간차는 다른 전이에 대해 다를 수 있다는 것이 주목된다.While these embodiments are relatively simple, as can be seen in FIG. 13, the overall transition time is, for example, the delay time (

It has the disadvantage of increasing by). In the example shown, the time difference is a fixed time difference, ie the same for all transitions, which is the preferred embodiment. It is noted that in the examples the time difference may be different for different transitions.

14 shows an example of an embodiment of the present invention that is not the case. Structures I and II show the transition from the initial state to the black state, where the initial states are white (W), light gray (G2), and dark gray (G1), followed by the transition to the final gray level (G1). do. In these structures the waveforms for the application of the reset potential difference of the longest duration (from white (W) to black (B)) are the same, starting at the same time and ending at the same time. No waveforms for other transitions exceed these start or end points. When comparing the left structure I with the right structure II, the onset of the shaking pulses shows the shift in time for all transitions except the longest transition (W-B-G1). As a result, a smooth effect occurs for all transitions except the longest one when two distributed groups are used using structures I and II.

')가 확립된다는 점에서 다르도록 배열되며, 모든 그룹에 대해 길이의 쉐이킹 펄스(P_shaking)가 후속되는 최대 시간 길이의 리셋 전위차(W-B)의 결합의 인가는 공통 시작 지점(t_start)과 종료 지점(t_end)을 구비하는 최대 시간 기간 내에 동기화되며, 모든 그룹과 전이에 대해 리셋 전위차의 인가는 시간상 상기 최대 시간 기간 이상으로 연장되지 않는다. 시간차는 시간차가 인가되는 모든 전이에 대해 일정한 길이일 수 있으며, 바람직하게는 일정한 길이이다. 이것은 구조 I과 II 사이의 차이를 단순화한다. 더 복잡한 실시예에서 시간차는 전이에 의존할 수 있다. 이점은 전이 시간이 증가하지 않으며, 단점은 더 복잡한 구동 구조가 구현되어야 한다는 것이다.In this embodiment, the driving means is characterized in that the application structure between groups (I, II) is a time difference between groups for transitions (G2-B, G1-B, BB) for onset of shaking pulses.

') Is arranged differently in that it is established, and the application of the combination of the reset time difference (WB) of the maximum time length followed by the _shaking pulse (P _shaking ) of length for all groups is the common start point (t _start ) and end Synchronized within the maximum time period with point t _end , the application of the reset potential difference for all groups and transitions does not extend beyond the maximum time period in time. The time difference may be of constant length for all transitions to which the time difference is applied, and is preferably of constant length. This simplifies the difference between structures I and II. In more complex embodiments the time difference may depend on the transition. The advantage is that the transition time does not increase, and the disadvantage is that more complex drive structures must be implemented.

11, 12 and 14 show an embodiment with negatively charged white particles and positively charged black particles. It is not important for the present invention whether the white particles are negatively charged and the black particles are positively charged, or vice versa.

)가 존재하는 이미 주어진 예와 비교될 수 있다. 도면의 중간에 추가적인 가능성이 도시되며 쉐이킹 기간은 동시에 시작하지만, 절반은 길이가 다르며, 이 예에서 구조 II에서의 쉐이킹 기간의 길이는 대략 구조 I의 길이의 절반이다. 이것은 또한 차이(

)를 유도할 것이며, 이 경우

=0.5P_shakingI=P_shakingII이다.

은 따라서 가장 긴 쉐이킹 시간 기간의 25%이상이다. 아래 부분에 유사한 상황이 도시되며, 오직 쉐이킹 기간만이 쉐이킹 기간의 종료에 서 동기화된다. 도 15의 중간과 아래 부분에 도시된 상황의 가장 극단적인 예에서 쉐이킹 기간(P_shakingII)의 길이는 0이 될 것이며, 즉 그룹들 중 한 그룹에서 쉐이킹 펄스는 인가될 것이며, 다른 것은 그렇지 않다.FIG. 15 illustrates how different shaking periods P _shakingI and P _shakingII may overlap or differ. Given the situation at the top, this means that the shaking periods P _shakingI and P _shakingII are the same length, but the shift (

) Can be compared with an already given example. An additional possibility is shown in the middle of the figure and the shaking periods start at the same time, but the half is different in length, in this example the length of the shaking period in structure II is approximately half the length of structure I. This is also a difference (

), In which case

= 0.5P _shakingI = P _shakingII

Is therefore more than 25% of the longest shaking time period. A similar situation is shown at the bottom, with only the shaking period being synchronized at the end of the shaking period. In the most extreme example of the situation shown in the middle and lower part of FIG. 15, the length of the shaking period P _shakingII will be zero, that is, the shaking pulse in one of the groups will be applied, and the other will not.

Especially when the lengths of the shaking periods are different, the structure is most preferably replaced. If the lengths of the shaking periods are different, the longest shaking period is usually the "right length", ie, as long as necessary to achieve the full effect of the shaking pulses. Shorter (or absent) shaking pulses, when applied repeatedly to the same group, induce a gray scale difference between the groups in time. By alternating the structure between the groups, this effect is eliminated because the average receives the same shaking pulses for different image transitions, all elements.

The application of different shaking potential differences between groups has the aforementioned positive effect of reducing the roughness of image conversion. Even if a smoother image transition is provided using the device and method according to the present invention, looking further, it is best for all groups to have substantially the same history of application of the shaking signal. By alternating the structure for the application of the shaking signal between the groups between the images, the difference between the groups is minimized. Thus, for example, if two groups A and B are used and two structures I and II are used for the application of the shaking potential difference, structure I is used for group A in the first frame and structure II For group B, structure II is used for group A in the next frame, group II is used for group B, and back in the next frame, structure I is used for group A, structure II is used for structure B, and so on. to be. The circulation or rotation of the structure will be used using two or more groups, which corresponds to the concept of "alternating" within the concept of the present invention. In the preferred embodiment the structures alternate with each change in the frame, but within the broader concept of the invention, the structures can alternate every n frames, where n is a prime number such as 1,2,3. The advantage of alternating every second or every three frames, rather than every frame, is simpler.

It is noted that a plurality of display elements divided into distributed groups may encompass all of the display screens of the display device and often do so, but this is unnecessary within the broad concept of the present invention, which may be associated with some of the larger screens. do. For example, there is a first part of the display screen where the image changes regularly and contains gray tones (eg photographs), while the other part of the display screen is completely black and white images (eg black characters on white background). When used to display), the present invention can be used for the first portion, not the second portion of the display screen.

In short, the present invention can be described as follows:

The electrophoretic display panel 1 includes a plurality of pixels 2; And drive means 100 for providing the reset pulse before applying the gray scale pulse and the shaking pulse between the application of the reset pulse and the gray scale pulse. The display panel includes two or more distributed groups of display elements. Each group is provided with its own structure (I, II) of shaking potential difference, and the application structure for the shaking potential difference is different for each group in different ways between the groups for at least some transitions, even if the occurrence of shaking pulses is minimal.

The division within the group can be fixed and the assignment of the structure to the group can be fixed (e.g., the first structure of the shaking pulses is provided for even rows of display pixels, and the second other structure is used for odd rows). Groups may be fixed, but assignments may vary between frames, for example, and groups do not need to be fixed (e.g., splitting in one frame occurs within two groups, each with odd and even rows). It is noted that in the following frame, three groups are used in the next frame).

Those skilled in the art will understand that the present invention is not limited by what is specifically shown and described in the foregoing. The present invention exists in combination of each and all new characteristic functions with each and all characteristic functions. Reference numerals in the claims do not limit their protective scope. The use of the verb "comprises" and its use does not exclude the presence of elements other than those described in a claim. Singular elements do not exclude the presence of a plurality of elements.

The invention also relates to any computer program comprising program code means for carrying out the method according to the invention when the computer program is executed on a computer, as well as computer readable for performing other methods to the invention when the program is executed on a computer. Any program product comprising program code means stored on a possible medium, as well as any program product means for use in a display panel according to the invention for performing the operations specific to the invention. Is implemented.

The invention has been described in terms of specific embodiments, which are illustrative of the invention and are not to be construed as limiting. The invention can be implemented in hardware, firmware or a combination thereof. Other embodiments are within the scope of the following claims.

The present invention relates to a method for driving an electrophoretic display device including a plurality of pixels, and is applicable to an electrophoretic display panel, a method for driving an electrophoretic display device including a plurality of pixels, and the like.

Claims (12)

As an electrophoretic display panel 1, An electrophoretic medium 5 comprising charged particles 6; A plurality of pixels 2; Electrodes (3,4) associated with each pixel (2) for receiving a potential difference, wherein the charged particles can occupy an extreme position near the electrode and an intermediate position between the electrodes; The extreme positions are associated with an extreme optical state of an electrode (3,4); And Drive means 100 An electrophoretic display panel 1 comprising: The driving means 100 is connected to each of the plurality of pixels 2. A reset potential difference having a reset value and a reset duration for causing the charged particles 6 to substantially occupy one of the extreme positions, and thereafter A gray scale potential difference for causing the particles 6 to occupy a position corresponding to the image information, and Arranged to provide a series of shaking potential differences during a _shaking time period P _shaking between the reset potential difference and the application of the gray scale potential difference, wherein the plurality of pixels comprises two or more distributed pixel groups A, B. The driving means 100 is arranged to provide its own application structure (I, II) of the shaking potential difference to each group of pixels, and the application structure (I, II) for the shaking potential difference is The shaking time period P _shaking applied to the groups A and B is a time difference (

, Differs from group to group in an inconsistent manner for at least some transitions of pixels from the initial optical state through the extreme optical state to the final optical state.

) Is at least 25% of the longest shaking time period for each group (

), Electrophoretic display panel. The method of claim 1, wherein the time difference (

) Is at least 50% of the longest shaking time period (

An electrophoretic display panel, characterized in that). 2. The driving means (100) according to claim 1, wherein the driving means (100) is arranged to provide a shaking potential difference such that the application structure (I, II) for the application of the shaking potential difference alternates between groups (A, B) between frames. Electrophoretic display panel. The electrophoretic display panel of claim 1, wherein the shaking time periods P _shakingI , P _shakingII for the groups are of equal length. The electrophoretic display panel according to claim 1, wherein the shaking time periods for different groups are different (P _shakingI ≠ P _shakingII ). 2. A driving device according to claim 1, wherein the driving means are arranged to provide each group with its own shaking potential difference, and the applying structures (I, II) for the shaking potential difference are transitioned for each group (

The electrophoretic display panel differs by a fixed time difference irrespective of). 2. The driving means according to claim 1, wherein the driving means has a time difference (I, II) between the groups of pixels.

') Are arranged different in that they are established between groups for these transitions (G2-B, G1-B, BB), in which the shaking pulse is followed by a combination of reset potential differences for a period shorter than the maximum period. However, for all groups of pixels, the application of a combination of reset potential differences WB of the maximum time length followed by a shaking pulse is synchronized with the maximum time period with a common start point t _start and end point t _end , and all The application of the reset potential difference for the group and the transition does not extend beyond the maximum time period t _start -t _end . A method for driving an electrophoretic display device comprising a plurality of pixels, wherein a reset potential difference is applied to the pixel prior to application of a gray scale potential difference to a pixel of the display device, the reset potential difference and the gray scale potential difference A shaking potential difference is applied during a _shaking time period P _shaking between application of the plurality of pixels, wherein the plurality of pixels includes two or more distributed pixel groups, and each group of pixels A and B has its own application structure of the shaking potential difference. (I, II) is supplied, and the application structure for the shaking potential difference is that the shaking time period P _shaking when the shaking potential difference is applied to the group (A, B) is a time difference (

), Which varies from group to group in a way that is not perfectly consistent for at least some transitions of pixels from the initial optical state to the extreme optical state to the final optical state.

) Is at least 25% of the longest shaking time period for each group (

A method for driving an electrophoretic display device comprising a plurality of pixels. 10. The method of claim 8, wherein the shaking potential difference is applied such that an application structure for application of the shaking signal is alternating between groups between frames. 9. The structure according to claim 8, wherein each group is supplied with its own structure for the shaking potential difference, and the application structure for the shaking potential difference is

A method for driving an electrophoretic display device comprising a plurality of pixels, which differ from group to group by a fixed time difference irrespective of). A computer program comprising program code means for performing a method according to the method claimed in claim 8 when the computer program is executed on a computer. A computer program product comprising program code means stored on a computer readable medium for carrying out the method according to the method as claimed in claim 8 when the computer program is executed on a computer.

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